Steam heating apparatus



Oct- 16, 193 D. N. CROSTHWAIT, JR 1,977,304

STEAM HEATING APPARATUS Original Filed Feb. 5, 1930 a Sheet-Sheet 1 06L 1934- D. N. CROSTHWAIT, JR 1,977,304

STEAM HEATING APPARATUS Original Filed Feb. 3, 1950 3 Sheets-Sheet 2 if p p ImferTor z/ am km Oct. 16, 1934.

D. N. CROSTHWAIT, JR 1,977,304 STEAM HEATING APPARATUS Original Filed Feb. 3, 1930 3 Sheets-Sheet 3 if i Eufentfr Patented Oct. 16, 1934" STEAM HEATING APPARATUS David N. Crosthwait, Jr., Marshalltown, Iowa, as-

' signor to 0. A. Dunham Company, Marshalh town, Iowa, a corporation of Iowa Original application February a, 1930, Serial No. 425,681. Divided and this application February 4, 1931, Serial No. 513,242

10 Claims.

This invention relates to a new and improved steam heating system, and more particularly to an improved apparatus for automatically feeding steam to the radiators at substantially the rate at which it is condensed. This application is a division of the application of David N. Crosthwait, Jr., Serial No. 425,681, filed February 3, 1930.

More specifically the invention contemplates the use of an improved valve in the steam supply pipe which is automatically controlled by variations in the pressure difierential existing between the supply and discharge sides of the radiator or radiators so that steam will be supplied at substantially the rate at which it is consumed.

This invention is particularly applicable and designed for use with a system of heating by sub-atmospheric steam, such as is disclosed in the patent to Dunham No. 1,644,114 granted October 4, 1927, although it will be apparent as the disclosure progresses that the principles of this invention are also applicable to a system utilizing steam at atmospheric or super-atmospheric pressures. ing system, the steam is circulated to and through the radiators or condensing spaces at sub-atmospheric pressures, which pressures are varied according to the amount of heat required for maintaining the space to be heated at the desired temperature. Steam traps are provided at the discharge side of the radiators, and a substantially constant pressure differential sufficient to insure the circulation of steam through the system is maintained between the supply and discharge mains regardless of what the absolute pressure of the steam within the radiators may be. Orifice plates are positioned in the several supply conduits in advance of the respective radiator units for apportioning the flow of steam to each radiator in accordance with the condensing capacity of that particular radiator.

It will be apparent that in a system such as has just been described, withthe steam trap closed and a certain sub-atmospheric pressure established in the return main, if the steam is supplied to the radiator more rapidly than it is condensed therein, the pressure in the radiator will be increased and consequently the pres sure differential between the supply and return sides of the radiator will be somewhat increased. On the other hand, if the steam condenses with in the radiator more rapidly than it is supplied, the pressure in the radiator will drop In this Dunham type of heatand consequently the pressure differential will decrease. According to the present invention these variations from a normal pressure differential are utilized to automatically operate a control'valve in the supply conduit whereby the flow of steam to the radiator, or radiators,

will be varied to compensate for this change from a normal pressure difierential. .Under ordinary circumstances the valve will assume a position of substantial equilibrium whereby the rate of steam flow to the radiator is just sufficient to satisfy the condensing requirements, the pressure differential remaining substantially constant.

The principal object of this invention is to provide a new apparatus for heating by steam, such as briefly described hereinabove and. disclosed more in detail in the specifications which follow.

Another object is to provide an improved ap- 7 paratus for regulating the rate of steam flow to a radiator or group of radiators in accordance with variations from a normal pressure differential between the supply and exhaust sides of the radiators.

Another object is to provide an improved valve operated by the difference between two fluid pressures for controlling the rate of steam flow through the valve.

Another object is to provide an improved apparatus for governing the rate of steam supply to a condensing system, which utilizes changes in pressure caused by variations in the diiierences between the rate .of steam supply and the rate of condensation to actuate the controlling means.

Another object is to provide in a system such as described hereinabove, means to out off the. steam supply when apredetermined maximum temperature has been reached in the space to be heated, and for again permitting the steam supply to be turned on when the temperature falls below this maximum.

Other objects and advantages of this invention will be more apparent from the following 06' detailed description of one approved form of apparatus capable of carrying out the principles .of this invention.

In the accompanying drawings:

Fig. 1 is an elevation showing the principal elements of a preferred form of sub-atmospheric steam heating system, in which the improve- -ments of this invention are incorporated.

I control system is also applicable for use with other types of heating systems, as will be hereinafter apparent. This heating system com-' prises a boiler or generator A, from which the steam flows through supply main B and the improved flow control valve C. The rate of steam supply is'controlled in the portion '3' of the supply main beyond the valve C, from which main B the radiators D are supplied. E are steam traps at the outlets of the radiators D, F is the return main, G is an accumulator tank for the condensate, H indicates generally the exhausting mechanism, J is the differential pressure controller for the exhausting mechanism, K indicates the electric control and signal panel, and L indicates a thermostat for cutting off the heat supply when a predetermined maximum temperature is reached in the space to be heated.

The controlled steam fiow in main B passes throughrisers 1 and inlet valves 2 into the respective radiators D. Suitable orifice. plates 2 (such asdisclosed in the Dunham patent hereinabove referred to) are interposed in the respective risers 1, preferably between the inlet valves 2 and the radiators (see Fig. 5) for proportioning the steam flows to the respective radiators in accordance with the size or condensing capacity thereof. The steam traps E are adapted to close when the radiators are filled with steam and prevent the escape of steam therefrom. When condensate and noncondensible gases accumulate in the radiators, the traps E will open and permit the condensate and non-condensible gases to flow out or be drawn out by the lower pressure maintained in the return side of the heating system. These gases and condensates flow out through pipes 3 into return main F and thence through the strainer 4 into the accumulator tank .G. In a similar manner, the condensate and gases accumulating in the portion 3' of the supply main pass out through float and thermostatic trap 5 into return main 1' and thence into the accumulator tank G. The exhausting mechanism H comprises a separator tank 6 and a pump 7, driven by motor 8, to withdraw water from the lower portion of tank 6 and force it through ejector 9 and thence back into the upper portion of tank 6 together with the gases and condensate which are withdrawn from accumulator tank G through pipe 10 and check valve 11 into the exhauster casing. The gases are vented from separating tank 6 through pipe 12 provided with outwardly opening check valve 13. When a certain amount of liquid has accumulated in tank 6, a float controlled mechanism, indicated generally at 14, operates to open a normally closed valve so that the pump 7 can force a part of the liquid out through pipe 16 provided ,with check valve 17, and thence through pipes 18, 19 and 20 back into the boiler.

The exhausting mechanism H is operated Whenever it is necessary to build up the pressure differential between'the supply and discharge sides of the heating system, or whenever it is necessary to transfer accumulated condensate from the accumulator tank G to the separating tank 6. The control mechanism J comprises a diiferential pressure controller 21 which automatically opens and closes a switch 22 which operates through starter 23 to control the motor 8. The diiferential pressure controller 21 comprises a diaphragm subjected on its opposite sides to the pressures existing in the supply and return sides of the heating system. For this purpose control pipes 24 and 25 extend to surge tanks 26 and 27 positioned in the horizontal section 28 of an equalizing pipe 29 LX- tending between the supply and return sides of the heating system, one end of pipe 29 being in communication with the supply main B and the other end extending down'to the accumulator tank G. A check valve 30 is positioned in the equalizing pipe between the relatively high pressure surge chamber 26 and the relatively low pressure surge chamber 27. This valve opens toward the high pressure side of the system and will normally remain closed unless for some reason a lower pressure temporarily exists in the supply main than the pressure in the return main, whereupon valve 30 will open so as to equalize the pressures. The control mechanism J will operate, in a well known manner as described more at length in the Dunham patent hereinabove referred to, to cause the exhausting mechanism H to operate whenever the pressure differential between the supply and discharge sides of the heating system falls below a predetermined minimum and to throw the exhausting mechanism out of operation whenever the desired pressure difierential has again been established. Also, a float controlled mechanism in the accumulator tank G (as disclosed in the Dunham patent) acts through switch mechanism 31 to start the operation of exhausting mechanism H whenever a predetermined amount of condensate has accumulated in the tank G.

A second equalizing pipe connection 32 extends between the foot of return main F and the boiler return pipe 18, and includes a normally closed check valve 33 opening toward the boiler. At such times as it may be desirable to operate the system at super-atmospheric pressures, or atsub-atmospheric pressures with the exhauster H out of operation,the stop-valve 33' in front of strainer 4 is closed, and the pipe connection serves to permit condensate to gravitate to the boiler.

In a shunt pipe connection B" extending closed in the Dunham patent hereinabove referred to. This reducing valve embodies balanced cut-01f valves whose movements to closed or opened positions are governed by the enclosed pressure diaphragm 34 and the adjustable weights 35 and 36. The diaphragm 34 is subject on one side to the steam pressure in supply main B through a pipe 37 connected at one end to the housing of the diaphragm and at the other to the supply main at a point sufiiciently remote from the valve M to be uninfluenced by pressure fluctuations in the vicinity of the valve. This reducing valve M is distinguished by the fact that the balancing weights 35 and 36 are $0 proportioned and positioned that a desired sub-atmospheric pressure may be maintained in the portion B of the supply main, while a somewhat higher pressure may exist in the supply main B leading from the boiler. By properly adjusting the weights 35and 36 any desired degree of vacuum may be maintained in the portion B of the supply main. Preferably a pressure gauge 38 is provided to indicate this vacuum or sub-atmospheric pressure.

It willbe noted that gate valves 39 are positioned in the shunt pipe line B at either side of reducing valve M, and similarly gate valves 40 are positioned at either side of the control valve C. Assuming for the moment that the valves 40 are closed and the valves 39 are open, the improved control valve C (hereinafter described) will be out of service and the steam pressure will be controlled entirely by the reducing valve M, in which case this system will operate substantially as set forth in the Dunham Patent No. 1,644,114, hereinabove referred to. The sub-atmospheric pressure of the steam supplied to the radiators D will be determined by a proper setting of the reducing valve M, and the exhausting mechanism H will be automatically operated whenever necessary so as to maintain the pressure in the return main F and exhaust side of the system lower, by a predetermined differential, than the pressure established in the supply side of the system by the reducing valve M. The radiators D will thus be maintained full of steam at the proper low pressure for giving the desired heat output.

The improved control valve 0 will now be described, referring to Figs. 2 and 3 in addition to Fig. 1. This valve comprises a casing 41 having an internal web 42 separating the high pressure chamber 43 from the relatively low pressure chamber 44. Inlet port 45 connects the relatively high pressure chamber 43 with the supply main B, and outlet port 46 connects low pressure chamber 44 with the controlled portion B of the supply main. The web 42 is formed with the aligned valve seats 4'7 and 48, with which cooperate respectively the connected and. substantially balanced valves 49 and 50. A removable closure plate 51 permits access to the upper portion of the casing 41. 'The lower portion of casing 41 is closed by a closure plate 52 having an outwardly projecting flange 53 secured to the casing by bolts 54, and an upwardly projecting flange 55 adapted to. center the plate 52 properly within the opening in the lower portion of the casing. The closure plate 52 is formed integrally with an upward extension 56 of the diaphragm casing member 57. This upper dished diaphragm casing member 5'7 is formed at its lower edge with an outwardly extending flange 58, and a similar lower diaphragm casing member 59 is formed on its upper edge with an outwardly extending flange 60. The two diaphragm casing members 5'? and 59 are clamped together at opposite sides of an enclosed flexible diaphragm 62 by means of a plurality of bolts 61 passing through the flanges 58 and and securing these flanges against the opposite faces of the peripheral portion of diaphragm 62. The chamber 63 within lower casing member 59 is open to the atmosphere through central passage 64. A pipe 65 leads from chamber 66 in the upper diaphragm casing to a surge chamber 67; which communicates through pipe 68 with the supply main B. the main diaphragm chamber 69 above dia- The chamber 66 is separated from phragm 62 by a web or bafile '70 designed to prevent the formation of convection currents in the liquid that accumulates above the diaphragm and thus prevent undue heating of the diaphragm 62 from the steam passing through casing 41. The upper portion '71 of a lower diaphragm casing is supported from the lower portion 59 of the upper diaphragm casing by means of a plurality of supporting struts '72.

The lower member 73 of this lower diaphragm casing is clamped to the casing member 71 by a plurality of bolts 74 so as to enclose a second flexible diaphragm 75, similar to the first described diaphragm 62. The chamber 76 above diaphragm is open to the atmosphere through central passage '77. The lower diaphragm chamber 78 is, connected through pipe 79 with a surge chamber 80 connected through pipe 81 with return main F. The surge chambers 67 and 80 may be conveniently positioned adjacent one another and connected by the supporting member 82, although there is no fluid connection between these two chambers.

Referring again to Fig. 2, the valve structure comprising the two movable valves 49 and 50 is provided at its upper end with an adjustable screw 84 having a lock nut 85 thereon, this screw 84 engagingthe cover plate 51 to limit the opening movement of the valves and thus prevent undue stresses on the diaphragms 62 and75. The upper end of a valve stem 86 is threaded in valve structure 83 at 87, and provided with a lock nut 88. The valve stem 86 is slidable through a guide 89 in the closure plate 52 and also passes vertically downward through the central passage 90 in web 70. The lower threaded portion 91 of stem 86 passes through diaphragm 62 and is sealed thereto by means of the diaphragm plates 92 and 93 held in place by nuts 94 and lock nut 95. The outer edges of the diaphragm plates are preferably curved, as

shown at 93', to prevent any cutting action on the diaphragm as it is flexed. The lower end of the threaded portion 91 of valve stem 86 is screwed into the yoke 96 and locked in place by nut 97. A lower valve stem 98 is similarly threaded into the lower side of yoke 96 and locked in place by nut 99. This-valve stem 98 is sealed in the lower diaphragm '75 by means of diaphragm plates 100 and 101, and nuts 102 and 103, in.the same manner as the upper valve stem is attached to the upper diaphragm. A lever 104 is intermediately pivoted at 105 to the lower end of a fulcrum link 106 suspended from lug 107 on diaphragm casing member 59. One end of lever 104 is pivoted at 108 in the yoke 96. The other armv of lever 104 slidably carries a weight 109'which may be adjusted to different positions lengthwise of the lever arm by fixing a pin 110 in any one of a series of holes 111 in the lever. It will be apparent that by adjusting the weight 109 outwardly on the, lever arm 104, the upward pressure exerted on the movable valve assembly will be increased.

It will be noted that opposed sides of the two connected diaphragms 62 and 75 are exposed tdatmospheric pressure, whereas the up- 4 return sides of the system. It will now be apparent that when this downward force exerted by the pressure differential just equals the upward force exerted by the adjustable weight 109, the valves will be in a state of rest or equilibrium. If the pressure differential increases above this fixed normal, there will be a tendency to overcome the effect of weight 109 and close the valves. On the other hand, if the pressure differential decreases, the weight 109 will overcome the fluid pressure and further open the valves.

In case the valves 49 and 50 are absolutely balanced, that is of equal area, the device will operate as above described. In case a semibalanced valve assembly is used, the varying pressure effect may be compensated for by employing larger diaphragm plates and 101 on one of the diaphragms, than the diaphragm plates 92 and 93 on the other diaphragm. This will change the efiective area of the flexible diaphragms and compensate for the unbalanced areas of the vtwo valves 49 and 50. balanced pressure due to the difference in elevation between diaphragms 62 and 75 may be compensated for by a proper variation in the relative sizes of diaphragm plates 92, 93 and 100, 101.

A small electric motor 112 is supported by bracket 113 from the lower diaphragm casing 73. This motor operates, through gearing enclosed in the casing 114, a crank arm 115, the motor being so controlled, as hereinafter described, as to move the crank arm 115 through successive arcs of 180 in the same direction. The lower end of a stem or connecting rod 116 is pivoted at 116' on crank arm 115. The block 117 is slidable on the upper portion of stem 116, and a compression spring 118 surrounding this stem is confined between block 117 and an adjusting nut 119 and lock nut 120. Oppositely projecting studs 121 on' block 117 are pivoted in the arms of yoke 122 formed on one end of lever 123, which is intermediately pivoted at 124 in the lugs 125 projecting downwardly from diaphragm casing 59. The other end 1260f lever 123 engages the yoke 96 so that when, the outer end 122 of the lever is elevated and the inner end 126 depressed, the valves 49 and 50 will be positively closed. When the outer arm 122 of the lever is lowered and the inner arm 126 is elevated, the yoke 96 will be released so that the valves will be returned entirely to the control of the difierential pressure mechanism first described.

The motor 112 is controlled automatically from thermostat L through the control panel K,

so that the. control valve C will be closed to entirely out off the steam supplied to the radiators when a certain maximum temperature has been reached in the space where thermostat L is positioned, and the valve C Will again be automatically returned to the control of the difierential pressure mechanism when the temperature in this space to be heated has fallen below the predetermined maximum. The operation of this portion of the mechanism will be best understood by reference to the wiring diagram shown in Fig. 4. The thermostat L, in the example here shown, comprises a member 127 which expands when heated so as to move a. spring arm 128 and through link 129 tip the pivoted yoke 130 carrying the tube 131, in which is enclosed a globule of mercury 132. In the position shown in Fig. 4, the member 127 is The un heated and has expanded so as to tip the tube 131 in such a direction that the globule 132 closes a circuit between the contacts 133 and 134 in one end of the tube. At a lower temperature the member 127 will contract so that the tube 131 will be tipped in the opposite direction and globule 132 will close a circuit through the contacts 135 and 136 in the opposite end of the tube. A wire 137 extends from the two central contacts 134 and 135, and wires 138 and 139 respectively extend from the end contacts 133 and 136. The three wires 137, 138 and 139 extend to the three terminals of the automatic control switch 140 of control panel K. This panel board is also provided with a line switch 141 to which the positive and negative leads 142 and 143 extend, and also with a pair of manual control switches 144 and 145. When the control mechanism is to be operated automatically by thermostat L, the manual control switches 144 and 145 will be open and automatic control switch 140 will be closed. Red signal light 146 and green signal light 147 are adapted to be illuminated respectively when the thermostat is calling for heat, or when no heat is required. The red and green signal lights 148 and 149 operate in a. similar manner when the respective manual control switches 144 and 145 are operated to turn the heat on or cut the heat off.

At 150 is indicated the automatic circuit controller for the valve operating motor 112. This comprises a fixed disc carrying a continuous contact ring 151, a pair of similar arcuate contact rings 152 and 153, and a smaller pair of arcuate contacts 154 and 155, the latter arcuate contacts being positioned to overlap the spaces between the ends of contacts 152 and 153. A movable contact arm 156 centrally pivoted at 157 is adapted to rotate in unison with the valve operating crank arm 115, in other words, this movable contact memberwill travel from the position shown in solid lines (Fig. 4) to the position shown in dotted lines, while crank arm- 115 ismoving through a corresponding arc of 180. The arm 156 carries connected contacts 158, 159 and 160 adapted to engage respectively with the ring 151, the pair of arcuate contacts 152 and 153, and the inner pair of arcuate contacts 154 and 155. The-inner pair of arcuate contacts 154 and 155 are connected by a wire 161, and wire 162 leads from contadt 165 to the series field 163 of the motor whose armature is indicated at 112. With the parts in the position shown in Fig. 4, the valve is opened, but the wire 162, contact 155, wire 161, contact 154, wire s 165, switch 140, wire 137, contact 134, mercury globule'132, contact 133, wire 138, switch 140, wire 166, arcuate contact 152, contact arm 156, circular contact 151, and wire 167 through switch 141 to the negative main 143. The motor will now commence to operate and will move the tact I60, contact arm I56, circular contact 151, and wire 167 to the negative main. When the movable contact arm 156 has reached the position shown in dotted lines, the contact 160 will pass off of the end of short arcuate contact 155, thus finally breaking the motor circuit and the parts will come to rest. The parts will now have been moved so as to positively close the valves 49 and 50 and shut ofi the. supply of steam to the radiators. I

When the temperature in the space to be heated has fallen sufliciently, the thermostat 127 will contract so that the mercury tube will be tilted in the opposite direction and a circuit completed between contacts 135 and 136. A motor operating circuit similar to that first described will now be completed from contact-136 of the thermostat through wire 139, switch 140, wire 168, arcuate contact 153, contact arm 156, circular contact 151 and thence as before to the negative main. This operating circuit will be broken when the arm 156 has returned (in a clockwise direction) to the position shown in solid lines, Fig. 4.

With the valve in the open position, as shown in Fig. 4, a circuit through red signal lamp 146 is completed-as follows: From positive lead 142,

through switch 141, wire 169, lamp 146, wire 1'70,

switch 140, wire 166, arcuate contact 152, switch arm 156, circular contact 151, and lead 167 back to negative main 143. When the valve is closed and contact arm 156 is in the dotted line position, a similar circuit will extend from wire 169 through wire 1'71, lamp 147, wire 1'72, switch 140, wire 168, arcuate contact 153, contact arm 156 to the circular contact 151 and thence back to the negative main. Thus whenever the valve is open, the red lamp 146 will be illuminated, and whenever the valve is closed and the system does not require heat the green lamp 147 will be illuminated.

In case the automatic control switch is opened, and it is desired to close the valve manually, the manually operated control switch 144 is closed, thus completing thefirst described motor operating circuit from wire 165 through wire 1'73, switch 144, and wire 174, to the wire 166 leading back to arcuate contact 152. In a similar manner the valves may be opened by closing the manually operated control switch 145, which completes a motor operating circuit from wire 165 through wire 1'75, switch 145 and wire 1'76 to the wire 168 and thence to the arcuate contact 153. When switch 144 is closed to cause the open valve to be moved-to closed position, a circuit through red signallamp 148 will be completed from positive main 142 through switch 141, wire 169, lamp 148, wire 1'77, switch 144, wire 1'74, wire 166, arcuate contact 152, movable arm 156, circular contact 151, and wire 167 to the negative main. This circuit will be broken and the red light will be extinguished whenthe arm 156 reaches the dotted line position and the valve has been closed. In a similar manner when switch 145 is closed to open the valve, the green light 149 will be illuminated by an energizing circuit passing from positive main 142 through switch 14.., wire 169, wire 1'78, lamp 149, wire 1'79, switch 145, wire 1'76, wire 168, arcuate con-' tact 153, contact arm-156, circular contact 151, and thence through wire 167 to the negative main. A control and signal system similar to that just described by way of example, is disclosed more in detail and claimed in the copendbeneath the boiler A, or the dampers or other heat controlling mechanism with which the generator is supplied. The weight 109 is set to establish a predetermined pressure differential between the supply and return sides of the system, and the difierential controller J should be regulated to maintain substantially the same or a somewhat smaller pressure differential. Assuming that the temperature in the building is below that at which thermostat L operates to close the valve C, and that the system is not yet filled with steam, the weight 109 will operate by gravity to open the valves 49 and 50 to permit a free flow of steam through the valve C. The exhausting mechanism I-I-will now be in operation to lower the pressure in the return main, but this exhausting action will extend throughout the system, since the traps E arenow open. The traps will remain open until the radiators D are filled with steam, and during this time the exhausting mechanism will be unable to establish any material pressure differential between the supply and return mains. When the steam fills the radiators D and reaches the traps E, the traps will automatically close, after which the exhausting mechanism H will be able to establish a lower pressure in the return main F than exists in the supply main B. As this pressure differential reaches the predetermined value, it will act on the diaphragms 62 and '75 to overcome the effect of weight 109 and tend to close the valves 49 and 50, thus throttling the how of steam to the radiators. As the operationof the valve is gradual, the valve in closing will reach a positionwhere the rate of steam supply to the radiators is approximately equal to the rate of steam consumption or condensation in the radiators, so that the difierential will remain substantially constant and the valve will tend to remain in.

a state of rest or equilibrium in that position for feeding steam to the system at the rate at which it is required. If, for any reason, the rate of steam supply'should exceed the desired rate of heat emission from the radiator, or that rate at which the radiators will condense steam to compensate for the heat loss from the building,-the pressure differentialswill increase and the valve C will tend to close. The condensing rate of the radiators will then exceed the rate at which steam is being supplied and the supply pressure will drop so that the difierential will diminish and the valve C will tend to open again under the influence of weight 109. It will be apparent that any increase in the pressure differential will tend to cause the valve to close and any decrease in the differential will tend to cause it to open, and that the gradual action of the valve in opening and closing bethat maintains the steam supply substantially equal to the condensing rate. It will thus be seen that the steam supply will seldom, if ever, be entirely cut off and a more constant temperature in the building will be maintained.

When this heating system is in properly balanced working adjustment, the heat emitted from the radiators should substantially equal the heat loss from the building, which will, of course, vary in accordance with variations in the outside temperature, being greater when the outside temperature is lower and vice versa. Steam should be condensed in the radiators at a constant rate and at atemperature just, sufficient to provide this desired constant heat emission from the radiators, and the rate of steam supplied through valve C should be just sufiicient to compensate for the rate at which the steam is condensed so as to maintain the radiators filled with steam at the requisite pressure and temperature.

Let us assume, for example, that the system is adjusted so as to maintain a pressure p in the radiators, and the exhaus ting apparatus H is automatically regulated by controller J to maintain a fixed pressure differential of, for example, one pound between the supply and return sides of the system, that is a pressure p-1 is maintained in the return main F. It is to be understood that the principal function of the exhausting ap-l paratus H is to maintain the pressure in the return main lower, by a substantially constant difierential, than the pressure-in the radiators, no matter what the absolute pressure in the radiators may be, so that the exhausting apparatus, in cooperation with the steam-traps E will keep the radiators purged of condensate and non-condensible gases. Obviously it is necessary to maintain a lower pressure in the return main than in the radiators so that the noncondensible gases will be drawn out when the steam traps open, and in order that this pressure diflerential may be maintained when the pressure within the radiators is atmospheric or sub-atmospheric, the exhausting mechanism is required to maintain a partial vacuum in the return main. Aside from this function, the exhausting mechanism has no direct control of the steam pressure within-.the radiators, but it does maintain this pressure difierential substantially constant, and variations in this pressure difierential, as thus established, are utilized to automatically control the valve C which in turn controls the absolute pressure and temperature of the steam within the radiators.

We have assumed that a pressure p has been established within the radiators, steam at this pressure and corresponding temperature con-v densing at a rate just suflicient to maintain the desired heat output from the heating system. Now let us assume that the outside temperature increases, there being a resultant decrease in the heat loss' from the building, so that less heat will be required from the radiators, consequently the condensing rate will be lowered. Since steam viS being supplied at a constant rate through valve C, and the steam cannot escape from the radiators except through condensation, the steam pressure will be temporarily built up within the radiators, for example, to p+1. At this time the pressure in the return main is still p1,and this increase in the pressure differential between the supply.

to p1. The exhausting apparatus wiH now go into operation to lower the pressure in the return main still further in order to re-establish the pressure-difierential necessary to withdraw noncondensible gases from the radiators. This will tend to cause valve C to open again and increase the steam supply to the radiators, but this valve will again be automatically closed as soon as the steam supply exceeds the demand and the pressure difl'erential increases, so that eventually an equilibrium will be established with the pressures, for example, p-1 in the radiators and p2 in the return main, if at this pressure the heat output from the radiators is just suflicient to maintain a fixed condensing rate.

On the other hand, assuming an initial pressure of p in the radiators and p1 in the return main, let us assume that the outside temperature falls so as to increase the heat' loss from the building and consequently increase the rate of condensation in the radiators. Since steam is being supplied at a constant rate, but is being condensed at an increased rate, the pressure in the radiators will drop, for example, to 2-1. The valve C will be automatically opened to increase the steam supply so thatthe pressure may be built up, for example, to p+2, assuming that at this pressure and consequent temperature the condensing rate will be constant to supply the desired heat emission. The exhausting apparatus will now permit the pressure in the return to build up to p+1, but will hold the return pressure at this desired differential below the supply pressure so that the radiators may be kept evacuated of condensate and non-condensible gases. All of these pressures may be, and preferably are, sub-atmospheric, but it will be noted that the automatic operation of the system is dependent entirely upon pressure difierences, the absolute pressures (and consequent temperatures) being immaterial to this operation, but these absolute pressures being automatically selected to establish the desired rate of heat output from the radiators.

If for any reason the temperature inside the building should exceed the predetermined temperature for which thermostat L is adjusted, this thermostat will operate through motor 112 and the mechanism previously described to positively close the valve C and cut ofl the supply of steam to the radiators D until the temperature has fallen below the permitted maximum. When the room temperature has fallen materially below this maximum, the valve will again be returned to the control of the differential pressure mechanism.

The control valves M and C may be used conjointly by leaving all of the valves 39 and 40 open and setting the weights on valve M so that it will only open when a substantially maximum vacuum has been reached in the heating system. Under all normal operations this valve M .will remain closed and the steam supply to the radiators will be controlled by valve C. However,. suppose that thermostat L has caused motor 112 to close the valve C then no steam will be supplied to the system. If this condition persists, no steam being supplied to the system, the traps E will cool oil and open, and the exhauster H will build up a maximum vacuum in the system at which time the valve M will automatically open to admit enough-steam to the system to keep the piping warm and prevent the radiators from becoming chilled. At the same time the heat emitted will be reduced to a minimum.

While this improved heating system has been here described and illustrated as utilizing only sub-atmospheric pressures, and this form of heating system will give most satisfactory results, it will be apparent that the valve C may be operated in the manner described in systems utilizing steam at atmospheric or super-atmospheric pressures. It is only essential that the necessary pressure differential be maintained between the supply and return sides of the system. If no pump or exhausting mechanism is used, it will benecessary to maintain a superatmospheric pressure, in the supply side of the system in order to provide the necessary pressure differential.

It is to be noted that in the construction of the improved control valve C, no stuffing boxes are required. One side of each of the movable diaphragms 62 and 75 is exposed to the atmosphere, whereas the pressure chambers at the other sides of the respective diaphragms will become filled with liquid so as to prevent the direct contact of steam with the diaphragms, thus effectively sealing the system against the loss of fluid pressure and prolonging the life of the diaphragms by protecting them from the direct action of the gases in the system.

While separate differential pressure controlled means have been here shown for controlling the exhausting mechanism H and the supply valve 0, it will be noted that since both of these elements are responsive to the same pressure changes, a single control apparatus could be used. For example, the switch 22, now operated by controller J, could be operated by the movements of the valve stem or similarly movable parts of control valve C, and the controller J could then be eliminated. There is, however, some advantage in utilizing two entirely separate diaphragm control mechanisms, one to operate the steam supply valve and the other the pumping mechanism, in that the pressure pipe connections can be separately located so as to secure the best control of each of these elements and to compensate for pressure drop due to the flow of steam or other fluids through the piping.

I claim:

1. Steam heating apparatus comprising a radiator, a steam supply conduit leading thereto, a discharge conduit leading from the radiator, a steam trap in the discharge conduit for permitting the escape of condensate and non-condensable gases from the radiator while preventing the escape of steam therefrom, means for maintaining a pressure. in the discharge conduit lower, by a substantially constant difference, than the pressure in the supply conduit, and means for automatically increasing or decreasing the rate at which steam is supplied through the supply conduit to the radiator in accordance with or decrease or increase respectively in the pressure differential between the supply and discharge conduits.

2. Steam heating apparatus comprising a radiator, a steam supply conduit leading thereto, a discharge conduit leading from the radiator, a steam trap in the discharge conduit for permitting the escape of condensate and non-condensable gases from the radiator while preventing the escape of steam therefrom, means for maintaining a pressure in the discharge conduit lower, by a substantially constant difference, than the pressure in the supply conduit, a valve in the supply conduit for controlling the rate at which steam is supplied to the radiator, means for automatically setting the valve in response to variations in the pressure differential between the supply and discharge conduits so that the size of the valve opening will be varied inversely with respect to changes in the pressure diiferential, and means for closing the valve When a predetermined temperature is attained ina space to be heated.

3. Steam heating apparatus comprising a radiator, a steam supply conduit leading thereto, a discharge conduit leading from the radiator, a steam trap in the discharge conduit for permitting the escape of condensate and non-condensable gases from the radiator while preventing the escape of steam therefrom, means for maintaining a pressure in the discharge conduit lower, by a substantially constant difference, than the pressure in the supply conduit, a valve in the supply conduit for controlling the rate at which steam is supplied to the radiator, and means for automatically setting the valve in response to variations in the pressure differential between the supply and discharge conduits 0 so that the size of the valve opening will be varied inversely with respect to changes in the pressure differential. v

4. Steam heating'apparatus comprising a radiator, a steam supply conduit leading thereto, a 5 discharge conduit leading from the radiator, a steam trap in the discharge conduit for permitting the escape of condensate and non-condensable gases from the radiator while preventing the escape of steam therefrom, exhaust- 0 ing means for reducing the pressure in the discharge conduit, a valve in the supply conduit for controlling the rate at which steam is supplied to the radiator, and pressure controlled means for automatically regulating the exhaust- 5 ing means to maintain a substantially constant pressure differential between the supply and discharge conduits and for varying the size of the valve opening to control the flow of steam-inversely with respect to variations in this pressure differential.

5. Steam heating apparatus comprising a radiator, a steam supply conduit leading thereto,

a discharge conduit leading from the radiator, a steam trap in the discharge conduit for permitting the escape of condensate and non-condensable gases from the radiator while preventing the escape of steam therefrom, exhausting means for reducing the pressure in the discharge conduit, a valve in the supply conduit for contr011ing Q the rate at which steam is supplied to the radiator, and means for automatically starting the exhausting mechanism into operation and for increasing the valve opening when the pressure differential between the discharge and supply conduits falls below a predetermined standard, and for stopping the exhausting mechanism and decreasing the valve opening when the pressure differential rises above this standard.

' 6. Steam heating apparatus comprising a radiator, a steam supply conduit leading thereto,

a discharge conduit leading from the radiator,

a steam trap in the discharge conduit for permitting the escape of condensate and non-condensable gases from the radiator while preventing the escape of steam therefrom, exhausting means for reducing the pressure in the discharge conduit, a valve in the supply conduit for controlling the rate at which steam is supplied to the radiator, means comprising pres- I,

sure connections with the supply and discharge conduits for stopping and starting the exhausting mechanism so as to maintain a substantially means comprising separate pressure connections,

with the supply and discharge conduits for automatically setting the valve in response to variations in this pressure differential so that the size of the valve opening will be varied inversely with respect to changes in the pressure differential.

' 7. Steam heating apparatus comprising a radiator, a steam supply conduit leading thereto, a discharge conduit leading from the radiator, a steam trap in the discharge conduit for permitting the escape of condensate and noncon densable gases from the radiator while preventing the escape of steam therefrom, exhausting means for reducing the pressure in the discharge conduit, a valve in the supply conduit for controlling, the rate at which steam is supplied to. the radiator, pressure controlled means for automatically regulating the exhausting means to maintain a substantially constant pressure differential between the supply and discharge conduits and for setting the valve to control the flow of steam in response to variations in this pressure difierential so that the size of the valve opening will be varied inversely with respect to changes in the pressure differential, and thermostatically controlled means for positively closing the valve when a predetermined maximum temperature is reached in the space heated by the apparatus.

8. Steam heating apparatus comprising a plurality of radiators, a supply conduit having branches communicating with the several radiators, a discharge conduit having branches leading from the several radiators, restricting gorifices between each radiator and the supply "conduit for limiting the amount of steam introduced into the radiator to the condensing capacity of the radiator, a steam trap between the outlet of each radiator and the discharge conduit, a valve in the supply conduit for varying the rate at which steam is supplied to the radiators, an exhausting means for reducing the pressure in the discharge conduit and pressure controlled means for automatically controlling the exhausting means and setting the valve so as to maintain a substantially constant pressure differential between the supply and discharge conduits sufficient to keep up circulation of fluids through the apparatus, and for varying the size of the valve opening inversely with respect to variations in this pressure differential.

9. Steam heating apparatus comprising a plurality of radiators, a supply conduit having branches communicating with the several radiators, a discharge conduit having branches leading from the several radiators, restricting orifices between each radiator and the supply conduit for limiting the amount of steam introduced into the radiator to the condensing capacity of the radiator, a steam trap between the outlet of each radiator and the discharge conduit, a valve in the supply conduit for varying the rate at which steam is supplied to the radiators, pressure controlled means, for automeans so as to maintain a substantially constant predeterminedpressure difierential between the supply and discharge conduits sufiicient to keep up the circulation of fluids through the apparatus, and separate pressure controlled means for automatically changing the effective size of thevalve opening inverselywith respect to variations in this pressure differential.

10. Steam heating apparatus comprising a .matically stopping and starting the exhausting.

plurality of radiators, a supply conduit having branches communicating with the several radiators, a discharge conduit having branches leading from the several radiators, restricting orifices between each radiator and the supply conduit for limiting the amount of steam introduced into the radiator to the condensing capacity of the radiator, a steam trap between the outlet of each radiator and the discharge conduit, a valve in the supply conduit for varying the rate at which steam is supplied to the radiators, pressure controlled means for automatically controlling the,

CERTIFICATE OF CORRECTION. Patent No. 1, 977,501;. October 16, 195A.

DAVID N. CROS'I'HWAIT, JR.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Page 7, first column, line 65, claim 1, for "'or" first occurrence, read a-; and that the said Letters Patent should be read Withthis correction therein that the same may conform to the record of the case in the Patent Office. Signed and sealed this 8th day of April, A. D. 19in.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

